(1) Field of the Invention
This invention relates to an alumina-base abrasion resistant material which can be sintered at low temperatures and has high abrasion resistance.
(2) Description of the Prior Art
Abrasion resistant materials composed of Al.sub.2 O.sub.3 or Al.sub.2 O.sub.3 and an additive such as ZrO.sub.2 have already been developed and used at places subject to severe mechanical abrasion and wearing, for example, at bent portions of chutes and ducts in powder or solid transport lines, impact-bearing parts onto which powder or solids fall down, etc. As production processes of alumina-base materials having still higher strength and abrasion resistance, it has also been known to add either one or 2-3 of MgO, CaO, Y.sub.2 O.sub.3, La.sub.2 O.sub.3, SiO.sub.2, Ta.sub.2 O.sub.5 and the like as grain growth inhibitor(s) or sintering agent(s) to Al.sub.2 O.sub.3 and then sintering the resulting raw batches. These processes however require sintering temperatures as high as 1,470.degree.-1,700.degree. C. and in some instances, need expensive additives such as Y.sub.2 O.sub.3. They are hence not preferred from the economical stand point. On the other hand, as an exemplary technique for lowering the sintering temperature, it has been reported that the sintering temperature for a dried 96% Al.sub.2 O.sub.3 body was lowered to 1,300.degree.-1,400.degree. C. by adding a compound additive of MnO.sub.2 and TiO.sub.2 or CuO and TiO.sub.2 to Al.sub.2 O.sub.3. This process however failed to achieve sufficient abrasion resistance.
As described above, conventionally-known alumina-base abrasion resistance materials required higher sintering temperatures upon their production. In some instances, they also required certain expensive additives. These requirements increased both energy and material costs, resulting in products of higher prices. On the other hand, it was unable to obtain products of any sufficient abrasion resistance in processes which employed additives to lower the sintering temperatures.